{	Problem: http://codeforces.ru/problemset/problem/29/A
 	Verdict: Accepted
}
var i,n,j:longint; a:array[1..110,1..2] of longint; r:boolean;
begin
read(n);
for i:=1 to n do begin
  read(a[i][1],a[i][2]);
  inc(a[i][2],a[i][1]);
end;
r:=false;
for i:=1 to n do
  for j:=1 to n do
    if (i<>j) and (a[i][1]=a[j][2]) and (a[j][1]=a[i][2]) then r:=true;
if r then write('YES') else write('NO');
end.